The present invention relates generally to a personnel location device or system, and, more particularly, to a sonar location monitor for indicating and/or determining the location of a person (i.e., a swimmer) in a water environment (such as a lake, pool, or beach swimming area).
Swimmer safety is an important concern in all water sports and activities. Lifeguards are assigned the responsibility of protecting the lives of the swimming public. However lifeguards can monitor only limited portions of a swimming pool, water park, or beach area and have particular difficulty in seeing what goes on near the bottom. In many instances, despite the presence of lifeguards, help for a swimmer in trouble comes far too late to prevent drowning. Even with adequate staffs, lifeguards often find it difficult to monitor large numbers of swimmers.
There have been attempts at developing automatic alarm equipment to warn the staff of swimmers in danger. Several of these inventions have focused on protecting children from drowning in backyard pools. (See, e.g., U.S. Pat. Nos. 3,953,843 3,969,712 4,079,364 4,121,200 4,187,502 4,747,085 5,049,859.) The devices described by these patents simply monitor the presence of an unauthorized swimmer or object in the pool. These devices are designed for very small pools and do not possess any location or tracking capabilities.
Some devices for detecting a swimmer in the water are known. Many of these detection methods rely on some variation of an acoustic technique. For example U.S. Pat. No. 4,337,527 describe a system that uses ultrasonic transmission through water to identify underwater targets. A human operator listening to headphones classifies the target and determines its location. U.S. Pat. No. 4,459,689 describes an apparatus utilizing combination energy transmitting and receiving transducer for detecting and locating objects within a plurality of zones. U.S. Pat. No. 4,635,242 describes an underwater signaling device utilizing acoustic sound generators. Several devices for detecting swimmers in distress are known. (See, e.g., U.S. Pat. Nos. 4,932,009 and 5,097,254.) However, these devices do not pinpoint the location of the distressed swimmer.
Therefore, of particular interest is the development of a system for monitoring a large number of swimmers in a pool, beach area, or water park. Such a system would be capable not only of monitoring the status of a large number of swimmers but would also be capable of pinpointing the location of a swimmer in distress with sufficient warning to permit a timely rescue.
All references cited herein are incorporated by reference.